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/* $NetBSD: tree.h,v 1.8 2004/03/28 19:38:30 provos Exp $ */
/* $OpenBSD: tree.h,v 1.7 2002/10/17 21:51:54 art Exp $ */
/* $FreeBSD$ */
/*-
* Copyright 2002 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
/*
* This file defines data structures for red-black trees.
*
* A red-black tree is a binary search tree with the node color as an
* extra attribute. It fulfills a set of conditions:
* - every search path from the root to a leaf consists of the
* same number of black nodes,
* - each red node (except for the root) has a black parent,
* - each leaf node is black.
*
* Every operation on a red-black tree is bounded as O(lg n).
* The maximum height of a red-black tree is 2lg (n+1).
*/
/* Macros that define a red-black tree */
#define RB_HEAD(name, type) \
struct name { \
struct type* rbh_root; /* root of the tree */ \
}
#define RB_INITIALIZER(root) \
{ NULL }
#define RB_INIT(root) \
do { \
(root)->rbh_root = NULL; \
} while (/*CONSTCOND*/ 0)
#define RB_BLACK 0
#define RB_RED 1
#define RB_ENTRY(type) \
struct { \
struct type* rbe_left; /* left element */ \
struct type* rbe_right; /* right element */ \
struct type* rbe_parent; /* parent element */ \
int rbe_color; /* node color */ \
}
#define RB_LEFT(elm, field) (elm)->field.rbe_left
#define RB_RIGHT(elm, field) (elm)->field.rbe_right
#define RB_PARENT(elm, field) (elm)->field.rbe_parent
#define RB_COLOR(elm, field) (elm)->field.rbe_color
#define RB_ROOT(head) (head)->rbh_root
#define RB_EMPTY(head) (RB_ROOT(head) == NULL)
#define RB_SET(elm, parent, field) \
do { \
RB_PARENT(elm, field) = parent; \
RB_LEFT(elm, field) = RB_RIGHT(elm, field) = NULL; \
RB_COLOR(elm, field) = RB_RED; \
} while (/*CONSTCOND*/ 0)
#define RB_SET_BLACKRED(black, red, field) \
do { \
RB_COLOR(black, field) = RB_BLACK; \
RB_COLOR(red, field) = RB_RED; \
} while (/*CONSTCOND*/ 0)
#ifndef RB_AUGMENT
#define RB_AUGMENT(x) \
do { \
} while (0)
#endif
#define RB_ROTATE_LEFT(head, elm, tmp, field) \
do { \
(tmp) = RB_RIGHT(elm, field); \
if ((RB_RIGHT(elm, field) = RB_LEFT(tmp, field)) != NULL) { \
RB_PARENT(RB_LEFT(tmp, field), field) = (elm); \
} \
RB_AUGMENT(elm); \
if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field)) != NULL) { \
if ((elm) == RB_LEFT(RB_PARENT(elm, field), field)) \
RB_LEFT(RB_PARENT(elm, field), field) = (tmp); \
else \
RB_RIGHT(RB_PARENT(elm, field), field) = (tmp); \
} else \
(head)->rbh_root = (tmp); \
RB_LEFT(tmp, field) = (elm); \
RB_PARENT(elm, field) = (tmp); \
RB_AUGMENT(tmp); \
if ((RB_PARENT(tmp, field))) \
RB_AUGMENT(RB_PARENT(tmp, field)); \
} while (/*CONSTCOND*/ 0)
#define RB_ROTATE_RIGHT(head, elm, tmp, field) \
do { \
(tmp) = RB_LEFT(elm, field); \
if ((RB_LEFT(elm, field) = RB_RIGHT(tmp, field)) != NULL) { \
RB_PARENT(RB_RIGHT(tmp, field), field) = (elm); \
} \
RB_AUGMENT(elm); \
if ((RB_PARENT(tmp, field) = RB_PARENT(elm, field)) != NULL) { \
if ((elm) == RB_LEFT(RB_PARENT(elm, field), field)) \
RB_LEFT(RB_PARENT(elm, field), field) = (tmp); \
else \
RB_RIGHT(RB_PARENT(elm, field), field) = (tmp); \
} else \
(head)->rbh_root = (tmp); \
RB_RIGHT(tmp, field) = (elm); \
RB_PARENT(elm, field) = (tmp); \
RB_AUGMENT(tmp); \
if ((RB_PARENT(tmp, field))) \
RB_AUGMENT(RB_PARENT(tmp, field)); \
} while (/*CONSTCOND*/ 0)
/* Generates prototypes and inline functions */
#define RB_PROTOTYPE(name, type, field, cmp) RB_PROTOTYPE_INTERNAL(name, type, field, cmp, )
#define RB_PROTOTYPE_STATIC(name, type, field, cmp) \
RB_PROTOTYPE_INTERNAL(name, type, field, cmp, static)
#define RB_PROTOTYPE_INTERNAL(name, type, field, cmp, attr) \
RB_PROTOTYPE_INSERT_COLOR(name, type, attr); \
RB_PROTOTYPE_REMOVE_COLOR(name, type, attr); \
RB_PROTOTYPE_INSERT(name, type, attr); \
RB_PROTOTYPE_REMOVE(name, type, attr); \
RB_PROTOTYPE_FIND(name, type, attr); \
RB_PROTOTYPE_NFIND(name, type, attr); \
RB_PROTOTYPE_FIND_LIGHT(name, type, attr); \
RB_PROTOTYPE_NFIND_LIGHT(name, type, attr); \
RB_PROTOTYPE_NEXT(name, type, attr); \
RB_PROTOTYPE_PREV(name, type, attr); \
RB_PROTOTYPE_MINMAX(name, type, attr);
#define RB_PROTOTYPE_INSERT_COLOR(name, type, attr) \
attr void name##_RB_INSERT_COLOR(struct name*, struct type*)
#define RB_PROTOTYPE_REMOVE_COLOR(name, type, attr) \
attr void name##_RB_REMOVE_COLOR(struct name*, struct type*, struct type*)
#define RB_PROTOTYPE_REMOVE(name, type, attr) \
attr struct type* name##_RB_REMOVE(struct name*, struct type*)
#define RB_PROTOTYPE_INSERT(name, type, attr) \
attr struct type* name##_RB_INSERT(struct name*, struct type*)
#define RB_PROTOTYPE_FIND(name, type, attr) \
attr struct type* name##_RB_FIND(struct name*, struct type*)
#define RB_PROTOTYPE_NFIND(name, type, attr) \
attr struct type* name##_RB_NFIND(struct name*, struct type*)
#define RB_PROTOTYPE_FIND_LIGHT(name, type, attr) \
attr struct type* name##_RB_FIND_LIGHT(struct name*, const void*)
#define RB_PROTOTYPE_NFIND_LIGHT(name, type, attr) \
attr struct type* name##_RB_NFIND_LIGHT(struct name*, const void*)
#define RB_PROTOTYPE_NEXT(name, type, attr) attr struct type* name##_RB_NEXT(struct type*)
#define RB_PROTOTYPE_PREV(name, type, attr) attr struct type* name##_RB_PREV(struct type*)
#define RB_PROTOTYPE_MINMAX(name, type, attr) attr struct type* name##_RB_MINMAX(struct name*, int)
/* Main rb operation.
* Moves node close to the key of elm to top
*/
#define RB_GENERATE_WITHOUT_COMPARE(name, type, field) \
RB_GENERATE_WITHOUT_COMPARE_INTERNAL(name, type, field, )
#define RB_GENERATE_WITHOUT_COMPARE_STATIC(name, type, field) \
RB_GENERATE_WITHOUT_COMPARE_INTERNAL(name, type, field, static)
#define RB_GENERATE_WITHOUT_COMPARE_INTERNAL(name, type, field, attr) \
RB_GENERATE_REMOVE_COLOR(name, type, field, attr) \
RB_GENERATE_REMOVE(name, type, field, attr) \
RB_GENERATE_NEXT(name, type, field, attr) \
RB_GENERATE_PREV(name, type, field, attr) \
RB_GENERATE_MINMAX(name, type, field, attr)
#define RB_GENERATE_WITH_COMPARE(name, type, field, cmp, lcmp) \
RB_GENERATE_WITH_COMPARE_INTERNAL(name, type, field, cmp, lcmp, )
#define RB_GENERATE_WITH_COMPARE_STATIC(name, type, field, cmp, lcmp) \
RB_GENERATE_WITH_COMPARE_INTERNAL(name, type, field, cmp, lcmp, static)
#define RB_GENERATE_WITH_COMPARE_INTERNAL(name, type, field, cmp, lcmp, attr) \
RB_GENERATE_INSERT_COLOR(name, type, field, attr) \
RB_GENERATE_INSERT(name, type, field, cmp, attr) \
RB_GENERATE_FIND(name, type, field, cmp, attr) \
RB_GENERATE_NFIND(name, type, field, cmp, attr) \
RB_GENERATE_FIND_LIGHT(name, type, field, lcmp, attr) \
RB_GENERATE_NFIND_LIGHT(name, type, field, lcmp, attr)
#define RB_GENERATE_ALL(name, type, field, cmp) RB_GENERATE_ALL_INTERNAL(name, type, field, cmp, )
#define RB_GENERATE_ALL_STATIC(name, type, field, cmp) \
RB_GENERATE_ALL_INTERNAL(name, type, field, cmp, static)
#define RB_GENERATE_ALL_INTERNAL(name, type, field, cmp, attr) \
RB_GENERATE_WITHOUT_COMPARE_INTERNAL(name, type, field, attr) \
RB_GENERATE_WITH_COMPARE_INTERNAL(name, type, field, cmp, attr)
#define RB_GENERATE_INSERT_COLOR(name, type, field, attr) \
attr void name##_RB_INSERT_COLOR(struct name* head, struct type* elm) { \
struct type *parent, *gparent, *tmp; \
while ((parent = RB_PARENT(elm, field)) != NULL && RB_COLOR(parent, field) == RB_RED) { \
gparent = RB_PARENT(parent, field); \
if (parent == RB_LEFT(gparent, field)) { \
tmp = RB_RIGHT(gparent, field); \
if (tmp && RB_COLOR(tmp, field) == RB_RED) { \
RB_COLOR(tmp, field) = RB_BLACK; \
RB_SET_BLACKRED(parent, gparent, field); \
elm = gparent; \
continue; \
} \
if (RB_RIGHT(parent, field) == elm) { \
RB_ROTATE_LEFT(head, parent, tmp, field); \
tmp = parent; \
parent = elm; \
elm = tmp; \
} \
RB_SET_BLACKRED(parent, gparent, field); \
RB_ROTATE_RIGHT(head, gparent, tmp, field); \
} else { \
tmp = RB_LEFT(gparent, field); \
if (tmp && RB_COLOR(tmp, field) == RB_RED) { \
RB_COLOR(tmp, field) = RB_BLACK; \
RB_SET_BLACKRED(parent, gparent, field); \
elm = gparent; \
continue; \
} \
if (RB_LEFT(parent, field) == elm) { \
RB_ROTATE_RIGHT(head, parent, tmp, field); \
tmp = parent; \
parent = elm; \
elm = tmp; \
} \
RB_SET_BLACKRED(parent, gparent, field); \
RB_ROTATE_LEFT(head, gparent, tmp, field); \
} \
} \
RB_COLOR(head->rbh_root, field) = RB_BLACK; \
}
#define RB_GENERATE_REMOVE_COLOR(name, type, field, attr) \
attr void name##_RB_REMOVE_COLOR(struct name* head, struct type* parent, struct type* elm) { \
struct type* tmp; \
while ((elm == NULL || RB_COLOR(elm, field) == RB_BLACK) && elm != RB_ROOT(head)) { \
if (RB_LEFT(parent, field) == elm) { \
tmp = RB_RIGHT(parent, field); \
if (RB_COLOR(tmp, field) == RB_RED) { \
RB_SET_BLACKRED(tmp, parent, field); \
RB_ROTATE_LEFT(head, parent, tmp, field); \
tmp = RB_RIGHT(parent, field); \
} \
if ((RB_LEFT(tmp, field) == NULL || \
RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) && \
(RB_RIGHT(tmp, field) == NULL || \
RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK)) { \
RB_COLOR(tmp, field) = RB_RED; \
elm = parent; \
parent = RB_PARENT(elm, field); \
} else { \
if (RB_RIGHT(tmp, field) == NULL || \
RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK) { \
struct type* oleft; \
if ((oleft = RB_LEFT(tmp, field)) != NULL) \
RB_COLOR(oleft, field) = RB_BLACK; \
RB_COLOR(tmp, field) = RB_RED; \
RB_ROTATE_RIGHT(head, tmp, oleft, field); \
tmp = RB_RIGHT(parent, field); \
} \
RB_COLOR(tmp, field) = RB_COLOR(parent, field); \
RB_COLOR(parent, field) = RB_BLACK; \
if (RB_RIGHT(tmp, field)) \
RB_COLOR(RB_RIGHT(tmp, field), field) = RB_BLACK; \
RB_ROTATE_LEFT(head, parent, tmp, field); \
elm = RB_ROOT(head); \
break; \
} \
} else { \
tmp = RB_LEFT(parent, field); \
if (RB_COLOR(tmp, field) == RB_RED) { \
RB_SET_BLACKRED(tmp, parent, field); \
RB_ROTATE_RIGHT(head, parent, tmp, field); \
tmp = RB_LEFT(parent, field); \
} \
if ((RB_LEFT(tmp, field) == NULL || \
RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) && \
(RB_RIGHT(tmp, field) == NULL || \
RB_COLOR(RB_RIGHT(tmp, field), field) == RB_BLACK)) { \
RB_COLOR(tmp, field) = RB_RED; \
elm = parent; \
parent = RB_PARENT(elm, field); \
} else { \
if (RB_LEFT(tmp, field) == NULL || \
RB_COLOR(RB_LEFT(tmp, field), field) == RB_BLACK) { \
struct type* oright; \
if ((oright = RB_RIGHT(tmp, field)) != NULL) \
RB_COLOR(oright, field) = RB_BLACK; \
RB_COLOR(tmp, field) = RB_RED; \
RB_ROTATE_LEFT(head, tmp, oright, field); \
tmp = RB_LEFT(parent, field); \
} \
RB_COLOR(tmp, field) = RB_COLOR(parent, field); \
RB_COLOR(parent, field) = RB_BLACK; \
if (RB_LEFT(tmp, field)) \
RB_COLOR(RB_LEFT(tmp, field), field) = RB_BLACK; \
RB_ROTATE_RIGHT(head, parent, tmp, field); \
elm = RB_ROOT(head); \
break; \
} \
} \
} \
if (elm) \
RB_COLOR(elm, field) = RB_BLACK; \
}
#define RB_GENERATE_REMOVE(name, type, field, attr) \
attr struct type* name##_RB_REMOVE(struct name* head, struct type* elm) { \
struct type *child, *parent, *old = elm; \
int color; \
if (RB_LEFT(elm, field) == NULL) \
child = RB_RIGHT(elm, field); \
else if (RB_RIGHT(elm, field) == NULL) \
child = RB_LEFT(elm, field); \
else { \
struct type* left; \
elm = RB_RIGHT(elm, field); \
while ((left = RB_LEFT(elm, field)) != NULL) \
elm = left; \
child = RB_RIGHT(elm, field); \
parent = RB_PARENT(elm, field); \
color = RB_COLOR(elm, field); \
if (child) \
RB_PARENT(child, field) = parent; \
if (parent) { \
if (RB_LEFT(parent, field) == elm) \
RB_LEFT(parent, field) = child; \
else \
RB_RIGHT(parent, field) = child; \
RB_AUGMENT(parent); \
} else \
RB_ROOT(head) = child; \
if (RB_PARENT(elm, field) == old) \
parent = elm; \
(elm)->field = (old)->field; \
if (RB_PARENT(old, field)) { \
if (RB_LEFT(RB_PARENT(old, field), field) == old) \
RB_LEFT(RB_PARENT(old, field), field) = elm; \
else \
RB_RIGHT(RB_PARENT(old, field), field) = elm; \
RB_AUGMENT(RB_PARENT(old, field)); \
} else \
RB_ROOT(head) = elm; \
RB_PARENT(RB_LEFT(old, field), field) = elm; \
if (RB_RIGHT(old, field)) \
RB_PARENT(RB_RIGHT(old, field), field) = elm; \
if (parent) { \
left = parent; \
do { \
RB_AUGMENT(left); \
} while ((left = RB_PARENT(left, field)) != NULL); \
} \
goto color; \
} \
parent = RB_PARENT(elm, field); \
color = RB_COLOR(elm, field); \
if (child) \
RB_PARENT(child, field) = parent; \
if (parent) { \
if (RB_LEFT(parent, field) == elm) \
RB_LEFT(parent, field) = child; \
else \
RB_RIGHT(parent, field) = child; \
RB_AUGMENT(parent); \
} else \
RB_ROOT(head) = child; \
color: \
if (color == RB_BLACK) \
name##_RB_REMOVE_COLOR(head, parent, child); \
return (old); \
}
#define RB_GENERATE_INSERT(name, type, field, cmp, attr) \
/* Inserts a node into the RB tree */ \
attr struct type* name##_RB_INSERT(struct name* head, struct type* elm) { \
struct type* tmp; \
struct type* parent = NULL; \
int comp = 0; \
tmp = RB_ROOT(head); \
while (tmp) { \
parent = tmp; \
comp = (cmp)(elm, parent); \
if (comp < 0) \
tmp = RB_LEFT(tmp, field); \
else if (comp > 0) \
tmp = RB_RIGHT(tmp, field); \
else \
return (tmp); \
} \
RB_SET(elm, parent, field); \
if (parent != NULL) { \
if (comp < 0) \
RB_LEFT(parent, field) = elm; \
else \
RB_RIGHT(parent, field) = elm; \
RB_AUGMENT(parent); \
} else \
RB_ROOT(head) = elm; \
name##_RB_INSERT_COLOR(head, elm); \
return (NULL); \
}
#define RB_GENERATE_FIND(name, type, field, cmp, attr) \
/* Finds the node with the same key as elm */ \
attr struct type* name##_RB_FIND(struct name* head, struct type* elm) { \
struct type* tmp = RB_ROOT(head); \
int comp; \
while (tmp) { \
comp = cmp(elm, tmp); \
if (comp < 0) \
tmp = RB_LEFT(tmp, field); \
else if (comp > 0) \
tmp = RB_RIGHT(tmp, field); \
else \
return (tmp); \
} \
return (NULL); \
}
#define RB_GENERATE_NFIND(name, type, field, cmp, attr) \
/* Finds the first node greater than or equal to the search key */ \
attr struct type* name##_RB_NFIND(struct name* head, struct type* elm) { \
struct type* tmp = RB_ROOT(head); \
struct type* res = NULL; \
int comp; \
while (tmp) { \
comp = cmp(elm, tmp); \
if (comp < 0) { \
res = tmp; \
tmp = RB_LEFT(tmp, field); \
} else if (comp > 0) \
tmp = RB_RIGHT(tmp, field); \
else \
return (tmp); \
} \
return (res); \
}
#define RB_GENERATE_FIND_LIGHT(name, type, field, lcmp, attr) \
/* Finds the node with the same key as elm */ \
attr struct type* name##_RB_FIND_LIGHT(struct name* head, const void* lelm) { \
struct type* tmp = RB_ROOT(head); \
int comp; \
while (tmp) { \
comp = lcmp(lelm, tmp); \
if (comp < 0) \
tmp = RB_LEFT(tmp, field); \
else if (comp > 0) \
tmp = RB_RIGHT(tmp, field); \
else \
return (tmp); \
} \
return (NULL); \
}
#define RB_GENERATE_NFIND_LIGHT(name, type, field, lcmp, attr) \
/* Finds the first node greater than or equal to the search key */ \
attr struct type* name##_RB_NFIND_LIGHT(struct name* head, const void* lelm) { \
struct type* tmp = RB_ROOT(head); \
struct type* res = NULL; \
int comp; \
while (tmp) { \
comp = lcmp(lelm, tmp); \
if (comp < 0) { \
res = tmp; \
tmp = RB_LEFT(tmp, field); \
} else if (comp > 0) \
tmp = RB_RIGHT(tmp, field); \
else \
return (tmp); \
} \
return (res); \
}
#define RB_GENERATE_NEXT(name, type, field, attr) \
/* ARGSUSED */ \
attr struct type* name##_RB_NEXT(struct type* elm) { \
if (RB_RIGHT(elm, field)) { \
elm = RB_RIGHT(elm, field); \
while (RB_LEFT(elm, field)) \
elm = RB_LEFT(elm, field); \
} else { \
if (RB_PARENT(elm, field) && (elm == RB_LEFT(RB_PARENT(elm, field), field))) \
elm = RB_PARENT(elm, field); \
else { \
while (RB_PARENT(elm, field) && (elm == RB_RIGHT(RB_PARENT(elm, field), field))) \
elm = RB_PARENT(elm, field); \
elm = RB_PARENT(elm, field); \
} \
} \
return (elm); \
}
#define RB_GENERATE_PREV(name, type, field, attr) \
/* ARGSUSED */ \
attr struct type* name##_RB_PREV(struct type* elm) { \
if (RB_LEFT(elm, field)) { \
elm = RB_LEFT(elm, field); \
while (RB_RIGHT(elm, field)) \
elm = RB_RIGHT(elm, field); \
} else { \
if (RB_PARENT(elm, field) && (elm == RB_RIGHT(RB_PARENT(elm, field), field))) \
elm = RB_PARENT(elm, field); \
else { \
while (RB_PARENT(elm, field) && (elm == RB_LEFT(RB_PARENT(elm, field), field))) \
elm = RB_PARENT(elm, field); \
elm = RB_PARENT(elm, field); \
} \
} \
return (elm); \
}
#define RB_GENERATE_MINMAX(name, type, field, attr) \
attr struct type* name##_RB_MINMAX(struct name* head, int val) { \
struct type* tmp = RB_ROOT(head); \
struct type* parent = NULL; \
while (tmp) { \
parent = tmp; \
if (val < 0) \
tmp = RB_LEFT(tmp, field); \
else \
tmp = RB_RIGHT(tmp, field); \
} \
return (parent); \
}
#define RB_NEGINF -1
#define RB_INF 1
#define RB_INSERT(name, x, y) name##_RB_INSERT(x, y)
#define RB_REMOVE(name, x, y) name##_RB_REMOVE(x, y)
#define RB_FIND(name, x, y) name##_RB_FIND(x, y)
#define RB_NFIND(name, x, y) name##_RB_NFIND(x, y)
#define RB_FIND_LIGHT(name, x, y) name##_RB_FIND_LIGHT(x, y)
#define RB_NFIND_LIGHT(name, x, y) name##_RB_NFIND_LIGHT(x, y)
#define RB_NEXT(name, x, y) name##_RB_NEXT(y)
#define RB_PREV(name, x, y) name##_RB_PREV(y)
#define RB_MIN(name, x) name##_RB_MINMAX(x, RB_NEGINF)
#define RB_MAX(name, x) name##_RB_MINMAX(x, RB_INF)
#define RB_FOREACH(x, name, head) \
for ((x) = RB_MIN(name, head); (x) != NULL; (x) = name##_RB_NEXT(x))
#define RB_FOREACH_FROM(x, name, y) \
for ((x) = (y); ((x) != NULL) && ((y) = name##_RB_NEXT(x), (x) != NULL); (x) = (y))
#define RB_FOREACH_SAFE(x, name, head, y) \
for ((x) = RB_MIN(name, head); ((x) != NULL) && ((y) = name##_RB_NEXT(x), (x) != NULL); \
(x) = (y))
#define RB_FOREACH_REVERSE(x, name, head) \
for ((x) = RB_MAX(name, head); (x) != NULL; (x) = name##_RB_PREV(x))
#define RB_FOREACH_REVERSE_FROM(x, name, y) \
for ((x) = (y); ((x) != NULL) && ((y) = name##_RB_PREV(x), (x) != NULL); (x) = (y))
#define RB_FOREACH_REVERSE_SAFE(x, name, head, y) \
for ((x) = RB_MAX(name, head); ((x) != NULL) && ((y) = name##_RB_PREV(x), (x) != NULL); \
(x) = (y))